1. Field of the Invention
The invention relates to a cosmetic and/or dermatological composition intended to moisturize the skin, both of the face and of the body, or even of the scalp, and the nails. It relates more particularly to a moisturizing composition of this type comprising at least one active agent which is conveyed via at least two distinct types of lipid vesicles.
The invention also relates to a cosmetic use of this composition for moisturizing the skin, and to a process for moisturizing the skin.
2. Discussion of the Background
Many examples are known of cosmetic or dermatological compositions intended for treating the skin, which have one or more active agents that are suitable for treating the skin and which are encapsulated in lipid spherules or vesicles (also known as liposomes).
Lipid spherules or vesicles are understood to refer to particles formed of a membrane consisting of one or more concentric lamellae, these lamellae containing one or more bimolecular layers of amphiphilic lipids encapsulating an aqueous phase. The aqueous phase may contain water-soluble active substances and the bimolecular layers of amphiphilic lipids may contain lipophilic active substances.
These spherules generally have a mean diameter of between 10 nm and 5,000 nm.
Among the many documents published regarding this matter, there may be mentioned the French Certificate of Addition 2,408,387 which describes a composition based on aqueous dispersions of ionic or nonionic lipid spherules encapsulating at least one active substance. More precisely, this document describes compositions containing at least two dispersions of spherules containing different active agents, for the purpose of obtaining a mixed system, that is to say a system in which a first dispersion of spherules containing a first category of active substance is combined with a second dispersion of spherules containing another category of active substance, which enables the two types of substances to act simultaneously at the time of treatment and possibly to obtain a synergistic effect which would not be produced if these two types of substances were made to act successively and separately.
Now, it is fully appreciated that it is important for the skin to be well moisturized, both at the surface and in the deeper layers of the epidermis and of the dermis. Exposure of the skin to the atmosphere results in dehydration, which must be compensated for by provision of moisturizing active agents.
It is well known that the skin consists of surface layers, the stratum corneum, and of deep layers, the live epidermis and the dermis. Now, specific delivery of such an active agent into the surface layers and, simultaneously, of the same or another active agent into the deep layers, was not known from the prior art.
Thus, there remains a need for a method and composition for simultaneously moisturizing the surface and deep layers of skin.